Tank cap with free travel

ABSTRACT

A tank cap with free travel to close a fuel tank of a motor vehicle can be screwed on a filler neck of the fuel tank so that it seals via rotational movement around a rotational axis and features an inner closure body and a cap body, which is pivoted on the closure body around a free travel angle delimited by a first limit stop and a second limit stop.

RELATED APPLICATIONS

[0001] This application claims priority under the Paris Convention based on German Utility Model Application No. 201 18 623.3, filed Nov. 15, 2001.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The invention relates to a tank cap with free travel to close a fuel tank of a motor vehicle, which can be screwed on a filler neck of the fuel tank so that it seals via rotational movement around a rotational axis and features an inner closure body and a cap body, which is pivoted on the closure body around a free travel angle delimited by a first limit stop and a second limit stop.

[0004] 2. Description of the Related Art

[0005] A tank cap is known from German printed patent specification 199 10 684. In the case of this known tank cap, the free travel is provided to prevent the cap from being unintentionally rotated by sheet metal edges that move in the case of an accident and being opened as a result. For this purpose the cap body is rotatable relative to the closure body, whereby a carrier of the one component is moved against a first and a second limit stop of the respective other component so that force is generated after the free travel is overcome. A spring, which holds the tank cap in a defined home position, can be arranged between the two components to guarantee that a free travel angle must always be overcome in the opening rotational direction before the generation of force becomes active. Another holding agent can be provided as an alternative to a spring, for instance an easy locking connection, which holds the tank cap at the second limit stop after it is screwed in and thus the locking force must be overcome in order to unscrew it.

[0006] In addition to these functional components, ventilation is normally provided in the interior of the tank cap, which is realized via a spring-loaded valve. In addition, most of the time known tank cap features a ratchet connection that guarantees a limitation of the torque in the closing direction so that overturning the screw connection or the bayonet connection in the filler neck and thus damage to the fastening mechanism can be avoided.

[0007] The known tank caps have the disadvantage that the limit stops must be realized using pins or comparable components that can only be produced very expensively with sufficient accuracy. Moreover, there exists the danger that once the pin lengths exceed a certain extent the limit stops cannot withstand the mechanical stress of the torque transmission and thus an error can occur. Finally, in most cases the known tank cap can be put together incorrectly so that a malfunction occurs from the limit stops not being arranged at the planned for positions, because the closure body relative to the cap body was put together rotationally misaligned relative to the target position for example.

[0008] Hence, those skilled in the art have recognized a need for a tank cap with free travel that can be mounted easily and is cost-effective to manufacture, whereby reliable force transmission from the cap body to the closure body remains guaranteed. The invention fulfills these needs and others.

SUMMARY OF THE INVENTION

[0009] Briefly and in general terms, the invention relates to a tank cap for closing a fuel tank of a motor vehicle. The cap can be screwed on a filler neck of the fuel tank so that it seals via rotational movement around a rotational axis and features an inner closure body and a cap body, which is pivoted on the closure body around a free travel angle (α) delimited by a first limit stop and a second limit stop. The closure body features a lower transverse support and the cap body features an upper transverse support connected rotatably around the rotational axis of the tank cap with the lower transverse support , whereby in the lower transverse support and/or the upper transverse support a contact surface recessed relative to at least one raised outer area is arranged.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010]FIG. 1 shows a side view of a tank cap;

[0011]FIG. 2 shows a sectional view of the tank cap shown in FIG. 1 with suction purification and free travel;

[0012]FIG. 3 shows a top view of the closure body of the tank cap shown in FIGS. 1 and 2;

[0013]FIG. 4 shows a three-dimensional view of the closure body shown in FIG. 3; and

[0014]FIG. 5 shows a view from below of the ratchet body of the tank cap shown in FIGS. 1 through 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] A tank cap with free travel that can be mounted easily and is cost-effective to manufacture includes a closure body that features a lower transverse support and a cap body that features an upper transverse support connected rotatably around the rotational axis of the tank cap with the lower transverse support. In the lower transverse support and/or the upper transverse support a contact surface recessed relative to at least one raised outer area is arranged.

[0016] Due to the development of the tank cap in accordance with the invention, malfunctions can now be avoided due to the design of the lower and upper transverse supports. The two components, which are preferably embodied to be bridge-like, lie on top of one another in a mounted state, whereby they penetrate each other partially. A recessed contact surface is arranged on one side or each on both sides in the area of the penetration so that the two transverse supports are pivoted on top of one another, whereby the contact surface is delimited at least on one side by a raised outer area, which in this case forms the limit stop.

[0017] It is preferred that the contact surface be embodied as an even surface, whereby it is unimportant for the function whether this recessed contact surface is arranged in the lower, the upper or in both transverse supports. As is also already the case with the known tank caps, the closure body can be embodied as a hollow cylindrical pot so that, in the case of lower and upper transverse supports that are embodied to be bridge-like, the lower transverse support is fastened with both its ends to the inner surface shell of the closure body. In this context “fastened” means that a connection is provided between the lower transverse support and the inner surface shell, whereby this can be realized either by an adhesive connection or a clamped joint or the component can also be manufactured from one piece together with the transverse support. The latter is offered in particular in cases where the lower closure body is manufactured of plastic in an injection molding process. In this case, the lower transverse support can be used as a sprue channel gate, which also prevents undesired material weakening from occurring as a consequence of solidified flow fronts in the area of the transverse support, which has special significance for the mechanical function of the tank cap.

[0018] The first and the second limit stop to delimit the free travel angle is formed in the case of the tank cap in accordance with the invention by the raised outer areas of the transverse support. These raised outer areas can be provided on both sides of the recessed contact surface, however, it is also possible, and particularly preferred if both transverse supports are provided with a recessed contact surface, that a raised outer area be provided only on one side of the recessed contact surface. In this case, the raised area of the lower transverse support assumes the function of the first limit stop and the raised area of the upper transverse support assumes the function of the second limit stop or vice versa.

[0019] The lower transverse support and the upper transverse support can be embodied as an even bridge, whereby the form of the bridge can be selected as desired to large extent. The raised outer areas can be designed in such a way that linear or surface pressure is produced when applying the opposite transverse support.

[0020] The upper transverse support can be connected with the closure body to be a single part, i.e., it can be molded in the lower side of the cap material. In addition, to the upper transverse support, the cap can also feature a wave-like mandrel, via which the cap body is connected rotatably with closure body. A torsion spring or even a horizontal helical spring can be integrated into this connection thereby guaranteeing a resetting of the cap into a defined position.

[0021] The special development of the first and second limit stops via the lower and upper transverse supports also makes it possible to realize an elastic force transmission due to an appropriate selection of material and shaping of the transverse support so that after overcoming the free travel the operator perceives the limit stop as a harmonic transition of the force transmission. The lower and the upper transverse supports are not specified in terms of their thickness,just the flexural strength and the ultimate tensile strength should be sufficiently amply dimensioned in a direction parallel to the rotational axis.

[0022] However, since stress in this direction does not occur directly, this does not produce a particularly high requirement for dimensioning. In the rotational direction, however, the raised outer areas must be connected with the lower cap body or with the closure body in such a way that they can transmit the torque. The maximum torque in this connection is prescribed as a rule by the operator's force, whereby an additional ratchet connection should be provided as a torque limitation so that damage can be avoided reliably.

[0023] In addition, known tank caps for the most part feature the possibility of suctioning ambient air. This compensates for negative pressure due to the volume withdrawn by the fuel preparation. For this purpose, in the case of the known tank caps, a spring-loaded valve is arranged in the pot-like closure body, which valve renders the influx of ambient air possible when applying negative pressure, and with atmospheric pressure or even excess pressure, seals the tank cap, however. Excess pressure can occur in particular in cases of accidents if the fuel tank is heated as a consequence of a vehicle fire. In this case, volatile and combustible gases must be prevented from exiting from the fuel tank at least for a certain period of time.

[0024] The disadvantage of this solution, however, is that dirt particles or drops of water are frequently suctioned along with the suctioned ambient air. Even if a fuel filter is provided in the area of the further mixture, these particles are undesirable, especially since the fuel filter as a rule is not in a position to filter out moisture from the fuel. In order to avoid this, the tank cap in accordance with the invention features at least one air collection space for the collection and interim storage of the suctioned ambient air. The air inlet in the filler neck is then formed by the front inlet openings, which connect the air collection space with the environment, and an overflow possibility, which connects the air collection space with the interior of the filler neck.

[0025] Due to this development of the tank cap, the air can now be calmed to begin with when passing through the cap into the air collection space, which results in foreign bodies and undesired gases being able to separate from the ambient air. Due to the overflow possibility, a portion of the calmed ambient air flows into the tank connection piece, whereby, as a result of the calming of the influxed air, dirt particles and gases separate so much from the calmed air that only purified air enters the filler neck. The dirt particles remain in the collection space, while, after the negative pressure suctioning the ambient air subsides, for instance when the motor is turned off and the supply of gasoline is interrupted, the other gases make their way through the inlet openings into the open air again.

[0026] In another preferred development of this tank cap, the air collection space is formed by an annular hollow space. This annular hollow space surrounds the filler neck, whereby it is preferred that the inlet openings be arranged in such a way that the ambient air can flow radially into the annular hollow space. For this purpose, several preferably also a plurality of inlet openings can be provided distributed equidistant over the circumference.

[0027] With this development, the closure body preferably features a supporting flange, which can extend outward in particular at a right angle to the rotational axis and rests with a lower surface on an edge of the filler neck. In the case of this development, the supporting flange is connected with the cap body, for example via a snap connection, and the inlet openings can be arranged in the transition area from the supporting flange to the remaining part of the closure body.

[0028] The tank cap is constructed in such a way that in the case of an accident a situation is avoided where the closure body is torn out of the filler neck. To this end, with the application of tensile force as a result of deformations to the outer cap body, a fracture possibility is provided, which already yields with the occurrence of such forces, which the screw connection or ratchet connection of the closure body with the filler neck might still be able to tolerate.

[0029] In order to form these safety features, the supporting flange can be provided with a groove-shaped recess on its underside or even on the upper side, which recess weakens the connection of the supporting flange with the remaining portion of closure body thereby providing a target fracture location. If the cap body is now connected with the outer edge of the supporting flange, with the occurrence of greater forces, the supporting flange will break off from the remaining part of the closure body thereby effectively avoiding a loosening of the closure body from the connecting piece. In addition to the annular groove, the inlet openings contribute to the weakening of the material in this case.

[0030] Of course, instead of an annular air collection space concentric to the rotational axis, several air collection spaces can be provided, which are connected with the environment via individual inlet openings. An overflow possibility is created from the air collection space, which overflow possibility renders the admission of the calmed air into the filler neck possible. This overflow possibility can be realized in a variety of ways, in the simplest case it is a leakage between the cap body and the closure body.

[0031] Normally, the cap body is an injection molded plastic part that features a hand grip projecting upward. This hand grip is manufactured in such a way in an injection molding process that a corresponding groove is produced on the hand grip on the underside of the cap body in the area of the bridge-like elevation. This groove is already adequate as an overflow possibility if an annular groove is provided as an air collection space. If, on the other hand, a plurality of air collection spaces is provided, an overflow possibility must naturally be created for each of the air collection spaces. This can occur, for example, by the underside of the cap body remaining spaced from the upper side of the supporting flange by using small distancing elements. The side edges of the supporting flange should however be clamped into the cap body in this design in such a way that direct entry of the ambient air into the connection piece is avoided so as not to diminish the effect of calming the inlet air.

[0032] As is already the case with the known tank caps, the closure body features a ratchet connection by virtue of which a force transmission occurs when closing the tank cap. If the torque applied by a person exceeds a specific amount, the ratchet connection slips through and damage to the plastic parts from too deep or too vigorous screwing into the often metallic filler neck can be avoided.

[0033] In the case of known tank caps, a spring-loaded component is used to realize the ratchet function, which component is connected with the cap body and slides off into the hollow cylindrical closure body on an inner running surface. Now it is preferred that this ratchet connection be realized via a collar manufactured of flexible material, which is also connected with the cap body. In this case, the closure body also features a pot body inserted into the filler neck, which has a running surface on its inner surface shell for the ratchet body embodied as a ring element.

[0034] The outer surface shell of the ratchet body and the running surface are each provided with locking teeth, whereby the locking teeth are embodied in such a way that they can slide off into one another in the closing direction and effect an interlocking hold in opposite opening rotational direction. To this end, two oblique planes preferably manufactured of plastic slide off onto one another in the closing direction, while steep locking edges engage in one another in the opening direction. By manufacturing the ratchet body and the pot body from a flexible plastic material such as polyamide, the spring can now be dispensed with and, along with a savings in manufacturing costs, an additional gain in safety is achieved since a malfunction from spring fracture is avoided. In addition, the assembly of the tank cap is clearly simpler due to this development.

[0035] Also in the case of the tank cap in accordance with the invention, in addition to the possibility of the ratchet body slipping through, a free movement of the cap body relative to the closure body can be provided. This free movement is realized by a rotatable placement, for example of the ratchet body on the cap body, if such is provided, or of the cap body directly on the closure body, whereby a first and a second limit stop are provided, which delimit the free travel angle. Normally an angle of between 90° and 180° is adequate as a free travel angle since, in accordance with the invention, greater rotations cannot occur in the case of an accident.

[0036] Additional features and advantages of the invention are yielded from the sub-claims and the subsequent description of the preferred exemplary embodiments on the basis of the drawings.

[0037]FIG. 1 shows a tank cap, which is formed by a closure body 1 and a cap body 2 placed on the closure body 1. The cap body 2 features a hand grip 9, which the user can use to unscrew the cap body 2 along with the lower closure body 1 from the tank connection piece of a motor vehicle for example.

[0038] In order to seal the tank connection piece, the closure body 1 features a laterally projecting supporting flange 1′, which is able to squeeze a seal between the edge of the tank connection piece and the lower side of the supporting flange 1′. To do so, the tank cap is rotated around the rotational axis D, whereby a free travel angle α is provided in the embodiment shown, which must first be overcome by the time the closure body 1 and the cap body 2 engage unrotatably in one another.

[0039]FIG. 2 shows a sectional side view of the tank cap shown in FIG. 1. Inside the closure body 1 the cap features a downward projecting pin concentric to rotational axis D, which is connected with an upper transverse support 3 and is pivoted in the area below this in a lower transverse support 4 of the closure body 1. The upper transverse support 3 supports itself on the lower transverse support 4, whereby a withdrawal safety mechanism is provided, which prevents the upper cap body 2 from being withdrawn from the closure body 1 in the direction of the rotational axis D. This can be formed by a special component or even be realized via a plug-type connector.

[0040] It is preferred that the withdrawal safety mechanism be formed, however, by the cap body 2 extending laterally over the supporting flange 1′ of the closure body 1 and being held on this supporting flange 1′ by lateral snap connections. A readjusting spring can be provided in the area of the cap body 2, which spring is preferably arranged horizontally and resets the cap to a defined limit stop so that it is not opened unintentionally in the case of an accident, but must always first overcome the free travel angle α in the opening direction.

[0041] The lower transverse support 4 features a raised outer area 5, which is formed in the case shown by a first raised outer area 5′ and a second raised outer area 5″. Arranged between these is the contact surface 6 on which the upper transverse support 3 supports itself. This can be seen especially well in FIGS. 3 and 5, whereby the delimitation of the free travel angle α is guaranteed by the raised outer areas 5′, 5″. In this connection, FIG. 3 shows a top view of the closure body 1, while FIG. 5 shows a view from below of the ratchet body 10 inserted into the closure body 1.

[0042] The ratchet body 10 is pivoted in a pot-like closure body 1, whereby in the lower area laterally projecting locking teeth made of flexible plastic material realize a limitation of the torsional force. In the closing direction, these teeth slip through starting at a specific torque and damage to the closing mechanism or the seal is precluded. These locking teeth engage in the corresponding catches of the closure body 1 in an interlocking manner in the opening direction and the opening torque can be transmitted in any case.

[0043]FIG. 4 shows the closure body 1 in a three-dimensional representation, whereby in this case the possibility of cleaning the suction air can be seen particularly well. To this end, the closure body 1 features a rotating groove in the upper area, which is connected via inlet openings 7 with the ambient air. From this groove the ambient air can flow via an overflow possibility 8, formed in this case (as shown in FIG. 2) by the hollow hand grip 9, into the interior of the closure body 1 and via an inlet opening arranged herein into the tank of the motor vehicle. The inlet opening is secured from gas escaping from the tank by a customary spring-loaded valve.

[0044] The inlet openings 7 are formed by bore holes distributed concentrically over the circumference of the groove, whereby the inflowing ambient air calms down to begin with in the groove and then, after solid matter is able to separate as a result of the calming of the flow within the groove, flows via the interior of the closure body 1 into the tank. The lower area of the supporting flange 1′ can be provided with a purposeful material weakening to form a target fracture location thereby yielding protection from unintentional withdrawal of the closure body 1 from the tank connection piece in the case of the effect of longitudinal force on the cap body 2 from an accident in that the supporting flange 1′ breaks off and is able to be removed together with the cap body 2.

[0045] It will be apparent from the foregoing that while particular forms of the invention have been illustrated and described, various modifications can be made without departing from the spirit and scope of the invention. Accordingly, it is not intended that the invention be limited, except as by the appended claims. 

What is claimed is:
 1. A tank cap to close a fuel tank of a motor vehicle, which can be screwed on a filler neck of the fuel tank so that it seals via rotational movement around a rotational axis and features an inner closure body and a cap body, which is pivoted on the closure body around a free travel angle delimited by a first limit stop and a second limit stop, characterized in that: the closure body features a lower transverse support and the cap body features an upper transverse support connected rotatably around the rotational axis of the tank cap with the lower transverse support, whereby in the lower transverse support and/or the upper transverse support a contact surface recessed relative to at least one raised outer area is arranged.
 2. The tank cap of claim 1 characterized in that the contact surface is embodied as an even surface in the center area of the lower transverse support and/or the upper transverse support.
 3. The tank cap of claim 1 characterized in that the lower transverse support and the upper transverse support are designed to be bridge-like, whereby the closure body is embodied as a hollow cylindrical pot and the lower transverse support is fastened with both its ends to the inner surface shell of the closure body.
 4. The tank cap of claim 3 characterized in that on the lower transverse support a projecting first raised outer area is arranged on one side in the direction of the upper transverse support and a projecting second raised outer area is arranged on the opposite side also in the direction of the upper transverse support, whereby to delimit the free travel angle, the first limit stop is formed by the first raised outer area and the second limit stop is formed by the second raised outer area.
 5. The tank cap of claim 3 characterized in that the lower transverse support and the upper transverse support each feature a contact surface, whereby the contact surface extends up to the edge on each of one of the sides of the lower transverse support and the upper transverse support, and a raised outer area extending over the plane of the contact surface is arranged on the respective other side.
 6. The tank cap of claims 3 characterized in that it features an upper supporting flange connected with the hollow cylindrical pot and extending outward at a right angle and supporting itself on an upper edge of a filler neck, whereby ambient air is able to enter through at least one air inlet in the tank cap in the connection piece, circumventing a connection piece seal against a-reflux seal and the tank cap features at least one air collection space for the collection and interim storage of the suctioned ambient air and whereby the air inlet is formed by the front inlet openings, which connect the air collection space with the environment, and an overflow possibility, which connects the air collection space with the interior of the filler neck.
 7. The tank cap of claim 6 characterized in that the air connection space is formed by an annular hollow space surrounding the filler neck.
 8. The tank cap of claim 7 characterized in that the annular hollow space is arranged in the cap body and connected in terms of flow with the environment via a plurality of passage openings forming the inlet openings.
 9. The tank cap of claim 8 characterized in that the annular hollow space is formed by a ring groove arranged in the supporting flange, which ring groove along with the underside of the cap body that closes it at the top forms the closed hollow space.
 10. The tank cap of claim 9 characterized in that the overflow possibility is formed by at least one groove-shaped overflow channel in the underside of the cap body.
 11. The tank cap of claim 10 characterized in that the cap body features a hollow bridge projecting outward to form a hand grip, whereby the overflow channel in the underside of the cap body is formed by the underside of the hollow bridge that is open at least partially at the bottom.
 12. The tank cap of claim 1 characterized in that the upper transverse support is connected with the cap body to be a single part.
 13. The tank cap of claim 1 characterized in that the lower transverse support is connected with the closure body to be a single part.
 14. The tank cap of claim 1 characterized in that the closure body is formed by a hollow cylindrical threaded pot that can be screwed on the filler neck and a permanently situated ratchet body that can be rotated in the threaded pot in one direction and solidly positioned in the opposite direction, whereby the closure body is connected with the ratchet body in the rotational direction around the rotational axis and solidly connected with the threaded pot in the direction longitudinal to the rotational axis.
 15. The tank cap of claim 14 characterized in that the ratchet body supports itself with locking teeth on a locking surface on the inner surface shell of the pot and the pot features corresponding stop teeth in the area of the locking surface so that the locking teeth engage in an interlocking manner in the opening rotational direction and slide off one another in the opposite direction.
 16. The tank cap of claim 15 characterized in that the ratchet body is formed by a ring element, which is inserted into the body of the pot, whereby the locking teeth are arranged on the outer surface shell of the ring element and the ring element is connected with the cap body. 